Nygolaimoides jairajpurii, Asgari & Mohammadlou & Eskandari & Abolafia & Peña-Santiago, 2025

Asgari, Mohsen, Mohammadlou, Mahsa, Eskandari, Ali, Abolafia, Joaquín & Peña-Santiago, Reyes, 2025, Description of Nygolaimoides jairajpurii sp. nov. from Iran, a new member of a rare genus (Nematoda, Dorylaimida, Thorniidae), Zootaxa 5660 (1), pp. 111-118 : 112-116

Nygolaimoides jairajpurii sp. nov.

( Figs 1–4 )

Material examined: Thirty specimens, 15 females and 15 males, in general in good state of preservation, a few nematodes somewhat flattened.

Measurements: See Table 1 .

Description: Adult: Slender to very slender (a = 34–55) nematodes of small to medium size, 0.96–1.38 mm long, females slightly larger than males (1.06–1.38 vs 0.96–1.16 mm). Body cylindrical, tapering towards both extremities, but more so towards the anterior end as the tail is short and rounded. Upon fixation, habitus variably curved ventrad, C-shaped in female and J-shaped in male. Two-layered cuticle, 1–1.5 µm thick throughout most body. Body pores indistinct. Lip region continuous with the adjacent body, 2.4–3.1 times wider than high, ca one-half (45–57%) of body diameter at neck base, perioral area conspicuously protruding or elevated, slightly triangular in median view. SEM observations: lips totally fused and with low button-like papillae each surrounded by a ring-like annulus and a pore at the center, oral field wide as inner labial papillae are close to outer labial papillae, consisting of a series of fine concentric incisures around the oral aperture. Amphid fovea cup-like, its aperture an elliptical slit ca 3.5 µm long or less than one-third of lip region diameter. Cheilostom a truncate cone 5–6.5 µm or 0.4–0.5 times the lip region diameter long, with comparatively thin walls. Odontostyle typical of the genus, 6.3–7.7 times longer than wide, shorter (0.7–0.9 times) than lip region diameter, 0.80–1.05% of body length, with aperture 2.5–3.5 µm long or up to two-fifths (23–39%) of its total length. Guiding ring simple, delicate. Odontophore rod-like, lacking any differentiation, 1.6–1.8 times the odontostyle length. Pharynx consisting of a more slender but muscular anterior section gradually enlarging into the basal expansion, which is 4.8–8.0 times longer than wide, 3.5–5.3 times longer than body diameter at neck base, and occupies less than half (39–46%) of the total neck length; gland nuclei often conspicuous, DN almost as large as S 1 N and these much larger than S 2 N, located as follows (n = 2): DO = 59–64, DN = 65–71, S 1 N = 78–82, S 2 N = 88–91. Pharyngo-intestinal junction consisting of a short and rounded cardia 6–12 x 10–15 µm, enveloped by intestinal tissue, its junction to the pharyngeal base with three small cardiac cells.

Female: Genital system diovarian, with both branches equally and well developed, the anterior 131–227 µm long or 11–20% of total body length each, the posterior 150–216 µm or 13–18% of body length. Ovaries variably large, 50–198 µm long, not always surpassing the oviduct-uterus junction. Oviduct 64–127 µm or 2.7–4.4 times the corresponding body diameter long, consisting of a slender, distal portion made of prismatic cells and an about twice longer than wide pars dilatata often containing sperm cells inside. Uterus a simple tube-like structure, 25–47 µm long or 1.0–2.0 body diameters long. Vagina extending inwards 10–12 µm, to ca one-third (31–38%) of body diameter: pars proximalis 4 x 7–9 µm with sigmoid walls, pars refringens consisting of (lateral view) two rounded sclerotized pieces 2 x 2 µm and a combined width of 4.5 µm, pars distalis 2 µm long. Vulva a very short longitudinal slit. Prerectum 1.4–2.3, rectum 0.9–1.3 anal body diameters long. Tail short and rounded, almost hemispheroid.

Male: Prerectum 2.5 and cloaca 1.3–1.4 times longer than body diameter at level of cloacal aperture. Genital system diorchic, with opposite testes, sperm cells spindle-shaped, 5.5–6.5 x 2–2.5 µm. In addition to the ad-cloacal pair, located at 4 µm from the cloacal aperture, there are four ventromedian supplements out the range of spicules, the most posterior of which is situated at 34–38 µm from the ad-cloacal pair, arranged into two pairs, the posterior pair close together (4–7 µm apart), meanwhile the anterior pair is situated at 16–25 µm from the posterior one and its supplements 8–17 µm apart. Spicules dorylaimoid, strongly curved ventrad, 1.4–1.6 times longer than body diameter and 5.8–6.9 times longer than wide: head 4.5–5.5 x 3.5–4 µm, occupying 14–18% of total length; median piece 1–2 µm wide and occupying one-fifth to two-fifths of maximum spicule diameter; posterior tip 1–1.5 µm; ventral hump poorly demarcated, at 6–8 µm or 29–27% of spicule length from its anterior end; curvature 110–122º. Lateral guiding pieces 6–8.5 x 1.5 µm, weakly curved ventrad. Gubernaculum hardly perceptible, ca 5 µm long. Tail rounded conoid, ventrally almost straight.

Diagnosis

The new species is characterized by its slender to very slender (a = 34–55) body 0.96–1.38 mm long, lip region continuous and 12–13.5 µm broad, odontostyle 9–11.5 µm long, neck 224–293 µm long, pharyngeal expansion 90–135 µm long, V = 49–55, female tail hemispheroid (7–10 µm, c = 110–163, ć = 0.4–0.6), male tail rounded conoid (14–20 µm, c = 53–71, ć = 0.7–1.0), spicules 29–34 µm long, four ventromedian supplements arranged in two pairs and with hiatus.

Separation from its relatives

The new taxon is easily distinguishable from other species of the genus by the number and arrangement of the ventromedian supplements. On the one hand, the four ventromedian supplements invariably present in all the males studied are unique within Nygolaimoides , four out of its six bisexual species bear only one ventromedian supplement, with N. albus always bearing two and N. zarrinensis bearing two in general, exceptionally, one or three. On the other hand, the arrangement of the four ventromedian supplements into separated pairs is exclusive of the new species too.

Besides, the new species resembles N. andrassyi Ahmad, Okada & Araki, 2003 ; N. fraternus Andrássy, 1987 and N. zarrinensis Zahedi, Niknam, Jabbari & Peña-Santiago, 2016 . It differs from N. andrassyi , only known to occur in Japan, in its more slender body (a = 34–55 vs a = 25–33), and shorter female tail (7–10 vs 13–14 µm, c = 110–163 vs c = 77–86). From N. fraternus , only known to occur in Hungary, in its more slender body (a = 34–55 vs a = 26–30), narrower lip region (12–13.5 vs 15–16 µm), and much shorter female tail (7–10 vs 15–17 µm, c = 110–163 vs c = 53–75). From N. zarrinensis , at present an Iranian endemism, in its larger general size, especially appreciable in females (1.06–1.38 vs 0.73–0.94 mm long body), wider lip region (12–13.5 vs 9.5–12 µm), longer neck (224–293 vs 162–194 µm) and pharyngeal expansion (90–135 vs 78–90 µm), more posterior vulva ( V = 49–55 vs V = 46–50), and shorter female tail (7–10 vs 11–15 µm, c = 110–163 vs c = 63–84).

Type locality and habitat

Northern Iran, Gilan Province, fuman County, Rudkhan Castle region (GPS coordinates: 49° 14’ 28’’ N, 37° 3’ 51’’ E; altitude: 715 m above sea level), where the new species was recovered from moss and rotten wood from inside the castle, collected on 3 November 2022.

Type material

Female holotype , five female paratypes and six male paratypes deposited at the Nematode Collection of the Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain. Twelve female paratypes and nine male paratypes deposited at the Nematode Collection of the Faculty of Agriculture, University of Zanjan, Zanjan, Iran.

Etymology

The specific epithet refers to the name in honor of Prof. M. S. Jairajpuri, the well-known India nematologist.

Remarks

This is the third species of the genus described from and only known to occur in Iran. Interestingly, the three species bear two to four (very occasionally one) ventromedian supplements, conversely to the remaining Nygolaimoides representatives that invariably bear only one ventromedian supplement.

Several living individuals were selected for molecular study, but due to the presence of symbiotic fungi in these individuals (probably due to habitat and feeding), the sequencing results were not suitable for analysis.

Figures

FIGURE 1. Nygolaimoides jairajpurii sp. nov. from Iran. A, B: Anterior body region, lateral median view; C: Vagina region; D: Pharyngeal expansion; E: Male, posterior body region; F: Spicule; G: Female, posterior genital tract; H: Lateral guiding piece; I: Male, caudal region and spicule. J: Female, posterior body region; K: Posterior ovary; L: Pharyngo-intestinal junction. (Scale bars: A–C, F = 5 µm; D, E, G, K = 20 µm; F, I, J, L = 10 µm; H = 2 µm.)

FIGURE 2. Nygolaimoides jairajpurii sp. nov. from Iran (Female, LM). A, B: Anterior body region, lateral median view; C: Posterior genital branch; D: Vagina; E: Pharyngeal expansion; F, G: Posterior body region. (Scale bars: A, B, D = 5 µm; C, E = 20 µm; F, G = 10 µm.)

FIGURE 3. Nygolaimoides jairajpurii sp. nov. from Iran (Male, LM). A: Posterior body region; B, C: Caudal region; D–F: Spicule; G: Lateral guiding piece; H: Sperm cells. (Scale bars: A = 20 µm; B, C = 10 µm; D–F, H = 5 µm; G = 2 µm.)

FIGURE 4. Nygolaimoides jairajpurii sp. nov. from Iran (SEM). A: Anterior region, lateral view; B: Lip region, en face view; C: Vulva, ventral view. Labels are as follows: af = amphidial fovea; oa = oral aperture; olp = outer labial papillae; ilp = inner labial papillae; v = vulva. (Scale bars = 2 µm.)